1. Field of the Invention
The present invention relates to a method for racemization of optically active N-substituted azetidine-2-carboxylic acid esters.
2. Description of the Related Art
An optically active N-substituted azetidine-2-carboxylic acid ester has been known as a useful intermediate for the production of pharmaceuticals and has been produced by an optical resolution as disclosed in WO98/02568 or EP827954 from a racemic mixture of the ester.
It has also been known that after resolution of a desired enantiomer of the N-substituted azetidine-2-carboxylic acid ester, the other enantiomer of the ester has been usually discarded with the exception of an optically active N-benzoyl azetidine-2-carboxylic acid ester which was susceptible of racemization for a further optical resolution.